Lighting devices for endoscopes



Mii EMBEMCM M. FouREsTlER ET AL 2,932,294

LIGHTING DEVICES FOR ENDOSCOPES pnil 12, 1960 Filed oct. 1o, 1955 2snee-wrmt 1 @y www www 2.932294 on mL 12a/ Amig L2,V 196@ Filed Oct. 10,1955 M. FOURESTIER ETAL LIGHTING DEVICES FOR ENDOSCOPES 2 Sheets-Sheet 2muy# i d. @se i tijtllllttlt still meurtres navieras ron amaneceresyApplicaton ctoher lf), 1955, Serial No. 539,632,

Claims priority, application 1ifrance October lf3, l95-ll1 Claims. (Cl.Mil-6) The present invention has for its object improvements in lightingdevices used in endoscopes, in which a transparent rod transmits intothe interior of the cavity to be illuminated, and at a very Wide fieldangle (50 and more), the light obtained from a source located at theexterior.

The invention, which enables the illumination of the cavity observed tobe increased, either by direct vision or by lateral vision, is moreparticularly but not exclusively applicable to the devices described intheV previous latent No. 2.699.770 of January lll, 1955.

ln these devices, thc radiation emitted by an external source of lightlocated laterally, is concentrated on the extremity of a straighttransparent rod which serves as a light guide, the image of the sourcebeing formed on.

'that extremity or in its immediate vicinity. lt can he shown that thcmost correct arrangement corresponds to thc case in which themagnification of the optical system is equal to one, that is to say tothe case in which the image of the source of light has the same size asthe source itself, and has the same dimensions as the upper extremity ofthe transparent rod.

After having been subjected to a reflection on a 90 flint prism ofwcll-dcfincd dimensions which enable the opening of the beam to bemaintained, the radiation is propagated along tho transparent rod andreaches the other extremity, after having been subjected to reflectionson the walls of the rod, the number of which increases asV the size ofthe opening of the beam itself increases.

The quantity of. light transmitted depends on the value of: thecocllcicnt of' reflection on the walls and on the coefficient oftransmission of the material of which the rod is formed. it is thusdesirable to use a rod of high trans .parcncy, and experience has shownthat transparent silica of optical quality gives satisfactory results.

The optimum conditions'rclating to reflections from the walls are thosewhich correspond to total reflection, for which the coefficient ofreflection is equal to unity. It would thus appear advantageous to use arod which is not provided with any coating, but, when the beam has alarge opening, serious difllcultics are -mct with in practice, due tothe tact that the rod becomes covered with mist, grease or any othersubstance during the use of the apparatus,

and the lighting eflieiency becomes thereby seriously rcduced. lor thisreason, it has been proposed to cover the rod With-a reflecting metallicdeposit. The coefficient of reflection is then that which exists betweenthe trans` parent substance and the reflecting deposit. Even whendeposits having the highest reflecting values are employed, theintensity of the radiation at the extremity of the rod is considerablyreduced by reason of the very large number of reflections. The resultobtained is still less satisfactory if the rod is glued, withoutreflecting deposit, inside a sheath, since, as the limiting angleincreases, there is only a total reflection for a beam of a. smallopening, and the rays which correspond to a larger opening becomeretracted in the glue and are absorbed by the Walls of the metallicsheath.

2,932,294 ,restanten apr. la, tesa When it is desired to obtain auniformly illuminated field of observation, it is essential that thewhole of the section of the rod which receives the light coming from thesource should itself be uniformly lighted. Theory shows that a straightlight-guide transmits `more, light than a curved lightguide. It is thuspreferable, whenever this is found possible, to use a straight rod, of'transparent silica for example. However, in the case of certainapplications, and especially in gastroscopy, it is absolutely necessaryto use a flexible and deformable guide.

In accordance with the present invention, with a view to inereasing'theillumination of a cavity to be observed, a lighting device forcndoscopes having a transparent rod which transmits to the interior ofthe cavity the light provided by a source situated on the exterior, ischaractei-ized by the fact that, over a very small length from each ofits extremities, the lateral parts of the rod are coated with areflecting deposit, and that the rod is mounted in a hermcficalIy-tightsheath by the intermediary of a water and gas-tight coupling between thesheath and the parts which are coated with the said reflecting deposits.a space filled with dry gas being kept between the sheath and the rod.The sheath is tight against humidity, grease and any other substance;thc water and gastight connection betwccn the sheath and the tube iseffected for example by means of a glue, a cement, rubber, ctc.

A further feature of the invention is that the transparent rod whichserves as a light-guide, does not reach the extremity of the endoscopictube, this extremity being then provided with a mirror (plane, curved orwith facets) which co-opcrates with the transparent rod in such a waythat a portion of the rays issuing from the rod is reflected from themirror so as to increase the illuminated field.

ln addition, there may bc flxcd at the extremity of the endoscopicoptical system, either a mirror or a prism, so as to reflect or todeflect the rays of light with a view to facilitating observation bylateral vision.

On the other hand, the invention provides that the lighting of the wholeof the section of the rod which rcccivcs the light. is uniform. lnparticular. thc entering face is trued-ofl' after assembly and it has nochamfcr and no inset. Finally. a feature of' the invention is that therod acting as a light-guide may be composite and formed of a number ofsections placed together inside a sheath, cach section having nochamfercd edges, no insetting and no diaphragm, at least one of thesesections being of flexible transparent material.

ln the attached drawings, there have been shown vari- .ous forms ofembodiment of the devices in accordance is to say in which it is desiredto illuminate the lateral walls of the cavity to be observed;

Fig. 3 shows how a mirror may bc fitted to the endo scopic tube in orderto facilitate lateral vision;

Fig. 4 is a view in axial cross section of the extremity 4 of anendoscope, and shows how a mirror fixed to the optical system of auendoscope enables the radiation to be concentrated on the zone observed,for lateral vision;

Fig. 5 is a view similar to that shown in Fig. 4, and shows how a prismfixed to the optical system of an endoscope can deflect laterally thebeam of light rays with a .View to directing the light on the lateralwall which is to be observed;

Fig. 6 is a view in cross-section of a light-guide which light guide.

iu a frontal plane l. tht` points- A1, A1,. a .wjth respect to the exitface considered as a pupil, at

`has been incorrectly mounted and which gives rise to shadow zones inthe'eld of observation;

Fig. 7 shows how a correct-mounting may be obtained; Fig. 8 shows a viewin axial cross-section ot a flexible light-guide in accordance with theinvention;

Fig. 9 is a vicwin axial cross-section of a modified In conformity withthe invention, the rod light-guide l lis placed inside a sheath 2 whichis proof against humidity,

a space filled with dry air being kept between the rod and the sheath.At the extremities 3 and 4, the rod is covered over a small portion ofits length, with a relleetf ing deposit. if the rod is for example oftransparent silica, the deposit may be comprised by a silvering 5 and 6covered with a coppcr'coating 7 and S. The whole is made tight to thesheath 2 by any suitable means (glue, cement, rubber, cto).

If it is desired to have an illumination uniformly distributed aroundthe axis ot the rod. the` lower extremity of tite rod is niven apolished surface perpendicular to the axis (see lng. 2n). lt is often anadvantage to give y the axis of the beam a direction which forms acertain i The extremity is their angle with the axis of the rod. cut-oilto a bevel, such as is shown in Fig. l.

When a lateral illumination is required, it is preferable to cut theextremity of the rod to a bevel shape and then to cover it with arellecting deposit (see Fig. 2b).

'the extremity of the transparent rod may also be cut to a bevel andpolished (see Fig. 3), but the rod does not reach the extremity of theendoscopic tube 9, the terminal part it) ot' which is covered with amirror il, which may bc a mirror having facets. a curved mirror or aplane mirror.

'there is generally passed through thc endoscopic tube an optical systemwhich permits ot observation and photography. Some of these opticalsystems are specially designed for lateral observation. ln accordancewith the invention, this observation is facilitated by providing theextremity of the optical'systcm 12 with a member 13 having a reilectingsurface M (sec Fig. ll) which cooperates with the mirror il to directthe :flux of light issuing from the rod 'l towards the region to beobserved.

A further device in accordance with the invention, and having the sameobject, is shown in Fig. 5. The radiation issuing from the rod 1 andthat reflected from the mirror il. pass through a flint prism 15 whichis rigidly fixed to thc optical system i6, and are deflected with a viewto giving a special illumination of the region to be observed.

There have been shown in Fig. 6 the phenomena which take place'in anassembly in which the whole of the entering face ot the rod is notuniformly lighted. If there exists on the entering face of. the rod azone A which is less brightly lit (or which is dark), the successive im*ages of this zone resulting from relleetion on the walls of the rod l.are formed iu the plane of the entering face at Al, A2. A3. ctc., theimages `farthest away corresponding to the grcatcst'number ofrcllcctious. At the exit, rc projected,

A'I, ACN., and give a number of dark Zones which are the more clearlymarked as the number ol` reflections is lower (center 'of thc field) andas the pupil is smaller, that is to say as the ratio of length todiameter becomes greater.

if the :fonc A hasthe form of a ring, there are formed in the frontalplanes at the exit of the rod, a series of rings A'i, AZ, A'3 which areespecially' visible at the center of the field and which become morepronounced as the length of the tube increases. for a given diameter.

Rings of this lsind are especially formed:

if. the beam of light rays is diaphragmcd, or-

If there exists a chamier on the edge of the rod, or

1f the top of the rod is inset.

van

It is these rings which are seen in `the shape of a darli zone in Fig,6, in which thc rod l is mounted by means of an inset at its entry faceand provides a field of light which hasrdark Zones in thel form ofrings. On the other hand, Fig. 7 shows a correct assembly with theentering face of the rod l trued-oll alter it has been mounted insidethe sheath 2. This assembly' gives light guides having a very highellicicncy and giving a uniform illumination of the field.Y

in order to produce a light guide oi rigid form, there may be employedwith advantage a straight or curved rod of transparent silica. This isavery transparent substance which can quite easily be given an opticalsurface and which possesses in addition the properties of being readilycovered by a very adhesive reflecting deposit, for example by silvering.Now, as has already been stated above, highly adhesive reflectingdeposits 5 and (i which are free from any defect, are necessary at thepoints of fixation of the rod t to the sheath 2 in order to obtain agood light ctliciency from the assembly.

in the case in which a flexible and deformable guide is necessary (ingastroscopy for example) a rod oi transparent and flexible material canbe employed and can be mounted, as has been indicated above. Butexperience has shown that it is very dillieult to obtain on suchsubstances reflecting Vdeposits which arc suliiciently adherent.

The arrangement oli ifig. ti shows a flexible guide produced inaccordance with the invention. The rod lightguide is a composite rodformed of two rigid end portions i7 and llt, for example of silica, hxcdto the extrcmitiesof a sheath t9 and a rod Ztl. of plastic material.very transparent and very llcsible, placed inside the sheath .,l)between thc two rigid cud portions, the plane extremities 20' of thesaid llcxihlc rod 2() being supported against the internal laces of tht`end portions. laeh cud portion is covered on its lateralvside in thevicinity of .one extremity, with a reflecting deposit constituted, forexample, by a silvcring 5 6, covered with a deposit of copper 7-8. Bymeans of a glue or on an appropriate binder. the end portion is fixed toa nickel tube '3122 which is rigidly fixed to the sheath t9 by means ofa suitable hcrmetically-tight joint 23-2-l (glue, cement, rubbenjoint,ete).

During the bending movements, in order to avoid any optical contactbetween the flexible rod 2t) and its sheath i9, there may be interposedbetween these two either a matt paper or a rough sheath 2S having anindex of refraction as low as possible.

In accordance with the invention, the entering and exit surfaces have noinset and are not chamfercd. in the same way, the contact surfacesbetween the rigid sections and the ilexible'sections should be perfectlytrued and polished and should have no chantier.

lt is not absolutely necessary that the three sections should have thesame diameter, but when the terminal portion of the guide should have adiameter less than that of the image of the source. there is anadvantage in utilising for the longest possible portion of the path.sections of greatest diameter. bor the saine angle of entry into thcrod, thc number ol' itllcclions increases in fact as the diameter of therod becomes smaller.

l'vcu in the case of total relleclion without metallic surface (a barerod), it is |u'cferabll.` to have few rcllcctions by reasonl of thelosses of light due to imperfections of the surface.

ln Figure 9 there is shown an :uraugemcut useful in cases where thccavity to be illuminated is small. whereas the guide adjacent the inletend may bc of la ger diameter. llcrc the guide is composed oi a numberof sections In, 1b and le of decreasing diameter. rlhe sections areplaced inside a generally conical slcalh 2a which is, again, moistureproof, and provides a .space filled with dry air between the rodsections and the sheath. Silvering may be provided as before at Sn, Sl),Gn and 6b, and over this there may be placed the covering of copper' 5as at 7a, 71),'8a and 8b. Again the whole is made tight to the sheath 2aby any suitable means 30 rubber, etc.).

The flexible guide which has just been described above can be used for alarge number of apparatus amongst t which may be cited gastroscopes,probes for trans-illumination of the tympanum, etc.

What we claim is:

1. Illuminating device for endoscopes and the like comprising atransparent rod for transmitting the light .from a source into a cavityto be illuminated: a hermeti- 4the extremities of the said sheath and otthe said rod.

2. In a device in accordance with claim l. a trans parent rod having asits lower extremity a polished surface normal to the axis of the saidrod.

3. In a device in accordance with claim 1, a transparent rod having itslower extremity inclined at an angle to the axis of' the said rod.

4. In a device in accordance with claim 1, a transparent rod having itslower extremity inclined at an angle to the axis of the said rod andcovered by a reecting deposit.

' 5. A device in accordance with claim 1, in combination with anendoscope having a tubular exploring means, a transparent rod which doesnot extend up to the extremity of the` said tubular exploring means, abevelled and polished extremity on the said transparent rod to deflectthe light coming from the said source through the said rod, and opticalmeans mounted at the extremity of the of sections in close and exactcontact to constitute the' saidtransparent rod, the diameters of thesaid sections decreasing from the entrant extremity to the exitextremity of the saidV rod.

9. In a device in accordance with claim 1, a number of sections in closeand exact contact to constitute the said transparent rod, the sectionsat the entrant extremity and theexit extremity being of rigidtransparent material, and the remaining sections being of ilexibletransparent material.

10. Illuminating device for endoscopes and the like comprising atransparent rod for transmitting the light from a source into a cavityto be illuminated, an entrant end portion of solid transparent material,an exit (glue, cement,

end portion oi solid transparent material, a section of flexibletransparent material, the entrant face of said flexible section being incontact with the exit face of the said entrant end portion, and the exitface ofthe section being in contact with the entrant face of the saidexit end pori tion, a rellecting deposit on the lateral part in thevicinity ofthe entrant extremity of the entrant end portion, arellecting deposit on the lateral part in the vicinity of the exitextremity of the said exit end portion, a metallic tube surrounding thesaid entrant end portion, a metallic tube surrounding the said exit endportion, a hermctically tight joint between each of the said endportions and the corresponding tube, a `flexible hermetically-closedsheath surrounding the said section in close contact and of ilexibletransparent material, hermetieally-tight joints between the extremitiesof the said sheath and the correspending metallic tubes, and a volume ofdry gas bctween'thc saidscction and the said sheath- 1l. Illuminatingdevice for endoscopcs and the like comprising a transparent rod fortransmitting the light from a source into a cavity to be illuminated, anentrant end portion of solid transparent material, an exit end portionof solid transparent material, a section of flexible transparentmaterial, the entrant face of said flexible section being in contactwith thc exit face of the entrant end portion and the exit face of thesection being in contact with the'entrant face of the said exit endportion, a reflecting deposit on the lateral part in the vicinity of theentrant extremity of the said entrant end portion, a reflecting depositon the lateral part in the vicinity of the exit extremity of the exitend portion, a metallic tube surround ing the said entrant end portion,a metallic tube surround ing the said exit end portion, ahcrmctically-tight joint between cach of the said end portions and thecorresponding tube, a flexible hcrmetically-elosed sheath surroundingthe said section ot' llexible transparent material, hermetically-tightjoints between the extremities of the said sheath and the correspondingmetallic tubes, a volume of dry gas between the said section and thesaid sheath, and a second sheath which is relatively rough and having arefractive index as low as possible between the said firstmentionedsheath and the said section.

References Cited in the file of this patent UNITED STATES PATENTS1,550,197 Berry Aug. 18, 1925 1,733,239 Roberts Oct. 29, 1929 1,751,584Hansell Mar. 25, 1930 1,965,865 Thompson July 10, 1934 1,968,997 DruckerAug. 7, 1934 2,176,620 Beam Oct. 17, 1939 2,235,979 Brown Mar. 25, 19412,420,772 Dalton May 20, 1947 2,424,064 Stegeman July 15, 1947 FOREIGNPATENTS 787,117 France June 24, 1935

